Light guide, light source apparatus, and electronic apparatus

ABSTRACT

A light guide is disclosed. The light guide includes an incident surface, an exit surface, and a light guide section. Light emitted from a plurality of light emitting devices disposed in line enters from the incident surface. The exit surface is formed in a shape causing light to be concentrated. The light which has entered from the incident surface exits from the exit surface. The light guide section is bent. The volume of the light guide gradually increases in a direction from the incident surface to the exit surface.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2006-304679 filed in the Japanese Patent Office on Nov.10, 2006, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light guide that guides light emittedfrom a light emitting device and causes the light to linearly exit. Thepresent invention also relates to a light source apparatus and anelectronic apparatus that use the light guide.

2. Description of the Related Art

As a light source used for a scanner, a multi-function machine, and soforth that read an image and so forth, a CCFL (Cold Cathode FluorescentLighting) lamp has been used. In recent years, to thin or miniaturizethe main body of an apparatus, a CIS (Contact Image Sensor) has beenused in an image reading section (as disclosed in for example paragraph“0026”, FIG. 1, Japanese Patent Application Laid-Open No. 2004-72152).The CIS has an LED (Light Emitting Diode) as a light source tominiaturize the apparatus. The use of the LED instead of the CCFL allowsthe startup time and the power consumption to decrease. In addition,since the LED is mercury free, it can contribute to prevention ofenvironmental contamination.

SUMMARY OF THE INVENTION

When a solid state light emitting device such as an LED is used as alight source, it appears that a light guide that homogeneously guideslight of the light emitting device to a reading object is used. In thiscase, it is practical that the light guide is linearly structured. As alight source apparatus including the linearly structured light guide ismoved, light can be radiated to the entire reading object.

In this case, when light of the light emitting device enters from oneend side or both end sides of the light guide, it would be difficult tocause light homogeneously exit from the light guide to the readingobject and provide a sufficient amount of light to the reading object.When many light emitting devices are used to increase the amount oflight, the apparatus would become large. In addition, light would beinhomogeneously radiated to the reading object.

In view of the foregoing, it would be desirable to provide a lightsource apparatus which is capable of homogeneously radiating light, alight guide used in the light source apparatus, and an electronicapparatus equipped with the light source apparatus.

In addition, it would be desirable to miniature or thin an electronicapparatus such as a scanner.

According to an embodiment of the present invention, there is provided alight guide. The light guide includes an incident surface, an exitsurface, and a light guide section. Light emitted from a plurality oflight emitting devices disposed in line enters from the incidentsurface. The exit surface is formed in a shape causing light to beconcentrated. The light which has entered from the incident surfaceexits from the exit surface. The light guide section is bent. The volumeof the light guide gradually increases in a direction from the incidentsurface to the exit surface.

According to this embodiment of the present invention, since the volumeof the light guide section gradually increases, it can effectively guidelight that enters from the incident surface and diffuses, condense thelight, and cause the condensed light to exit from the exit surface. Whenthe light guide section is bent at a proper angle, light that entersfrom the incident surface is bent at the desired angle and the lightexits from the exit surface. As a result, while the optical path lengthis kept as large as possible, the light can be diffused andhomogeneously radiated. In addition, the light guide and the electronicapparatus equipped therewith can be miniaturized or thinned.

“The light guide section is bent” may refer to the state of which thelight guide section is bent with a clear bending line. Instead, “thelight guide section is bent” may refer to the state of which the lightguide section is gradually bent without a bending line.

In an embodiment of the present invention, the exit surface isblast-finished. As a result, while light is condensed and scattered onthe exit surface, the light exits from the exit surface. Thus, light ismore homogeneously radiated to the radiating object than the plane thatis not blast-finished.

In an embodiment of the present invention, the light guide section isdisposed on a far side of a radiating object and has a side surfacewhich is bent at an angle in a range from 120° to 150°. When the sidesurface is bent in the range, leakage of light from the side surface canbe suppressed. As a result, the amount of light that exits from the exitsurface can be increased.

In an embodiment of the present invention, the exit surface has aplurality of light condensing surfaces in a direction of which theplurality of light emitting devices are disposed. As a result, theplurality of light condensing surfaces contribute to homogenization oflight that exits from the exit surface.

In an embodiment of the present invention, the light incident surface isformed in a shape which causes light to diffuse. As a result, incidentlight that enters from the incident surface is effectively diffused.This structure contributes to homogenization of light.

According to an embodiment of the present invention, there is provided alight guide. The light guide includes an incident surface, an exitsurface, and a light guide section. Light emitted from a plurality oflight emitting devices disposed in line enters from the incidentsurface. The exit surface is formed in a shape causing light to beconcentrated. The light which has entered from the incident surfaceexits from the exit surface to a light radiating object. The light guidesection has a first side surface disposed on a near side of the lightradiating object and a second side surface disposed on a far side of thelight radiating object and bent from the first side surface at a firstangle and guides the light from the incident surface to the exitsurface.

According to this embodiment, since the second side surface is formedsuch that it is bent at the first angle, the optical path length can bekept as large as possible. As a result, light that enters from theincident surface can be homogenized. In addition, since the light thatenters from the incident surface and is bent at the predetermined angleexits from the exit surface, the light guide and the electronicapparatus can be miniaturized. In addition, light can be caused to becondensed and to exit from the exit surface. As a result, linear lightcan be caused to effectively exit.

In an embodiment of the present invention, the first side surface has afirst reflection surface connected to the incident surface, and a secondreflection surface connected to the first reflection surface at a secondangle which is smaller than the first angle and to the exit surface.When the light condensing state of the exit surface, the first angle,and the second angle are properly set, light that travels to the exitsurface properly spreads. As a result, the line can be substantiallycollimated on the exit surface formed in the light condensing shape.Thus, well-shaped light, namely accurately liner shaped light, can beradiated.

In an embodiment of the present invention, the second side surface has athird reflection surface which is connected to the incident surface andwhich is gradually apart from the first reflection surface as the thirdreflection surface is apart from the incident surface. As a result,light that enters from the incident surface can be guided without a lossof the amount of light.

In an embodiment of the present invention, the light guide section has ashutter section which blocks part of light passing from the incidentsurface to the exit surface and which is formed between the firstreflection surface and the second reflection surface such that theshutter section is recessed from the first side surface. As a result,excessive light that tends to spread and that exits from the end regionof the exit surface can be caused to exit from the center region of theexit surface.

According to an embodiment of the present invention, there is provided alight source apparatus. The light source apparatus includes a pluralityof light emitting devices and a light guide. The plurality of lightemitting devices is disposed in line. The light guide has an incidentsurface from which light emitted from the plurality of light emittingdevices enters, an exit surface which is formed in a shape causing lightto be concentrated and from which the light which has entered from theincident surface exits, and a light guide section which is bent andwhose volume gradually increases in a direction from the incidentsurface to the exit surface.

According to an embodiment of the present invention, there is providedan electronic apparatus. The electronic apparatus includes a pluralityof light emitting devices, a light guide, and a photoelectric convertingdevice. The plurality of light emitting devices is disposed in line. Thelight guide has an incident surface from which light emitted from theplurality of light emitting devices enters, an exit surface which isformed in a shape causing light to be concentrated and from which thelight which has entered from the incident surface exits, and a lightguide section which is bent and whose volume gradually increases in adirection from the incident surface to the exit surface. Thephotoelectric converting device receives the light which has exited fromthe exit surface and has reflected by a light radiating object andconverts the reflected light into an electric signal.

Thus, according to embodiments of the present invention, light can behomogeneously radiated to the radiating object. In addition, the lightguide, the light source apparatus, and the electronic apparatus can beminiaturized or thinned.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of a best mode embodiment thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein similar reference numerals denote similar elements, inwhich:

FIG. 1 is a perspective view showing a light source apparatus accordingto an embodiment of the present invention;

FIG. 2 is a schematic diagram showing the light source apparatus viewedin the direction of arrow A shown in FIG. 1;

FIG. 3 is a plan view showing a part of the light source apparatus;

FIG. 4 is a sectional view showing a carriage into which the lightsource apparatus has been built;

FIG. 5 is a perspective view showing a scanner apparatus as an exemplaryelectronic apparatus equipped with a carriage;

FIG. 6 is a schematic diagram showing a theory of an optical systemdisposed in the carriage;

FIG. 7 is a schematic diagram showing a simulation of light beams thatpass through a light guide;

FIG. 8 is a schematic diagram showing an illuminance distributioncharacteristic of the light source apparatus according to the embodimentof the present invention;

FIG. 9 is a schematic diagram showing an illuminance distribution in thecase that light emitting devices are disposed at both ends of a lightguide plate;

FIG. 10 is a schematic diagram showing an illuminance distribution inthe case that a plurality of light emitting devices are disposedimmediately below the light guide plate;

FIG. 11A and FIG. 11B are graphs showing startup times of a CCFL and anLED of the related art;

FIG. 12 is a side view showing a light source apparatus according toanother embodiment of the present invention;

FIG. 13 is a schematic diagram showing a simulation of light beams thatpass through a light guide shown in FIG. 12;

FIG. 14 is a schematic diagram describing a function of a shuttersection of the light source apparatus;

FIG. 15A is a schematic diagram showing a simulation of light beams thatpass through the light guide in the case that angle θ2 has been set tolarger than 150°;

FIG. 15B is a schematic diagram showing a simulation of light beams thatpass through the light guide in the case that angle θ2 has been set tosmaller than 120°;

FIG. 16 is a plan view showing a part of a light source apparatusaccording to another embodiment of the present invention;

FIG. 17 is a plan view showing a part of a light source apparatusaccording to another embodiment of the present invention;

FIG. 18 is a plan view showing a part of a light source apparatusaccording to another embodiment of the present invention;

FIG. 19A is a schematic diagram showing an illuminance distribution of aleft half of the light source apparatus shown in FIG. 18; and

FIG. 19B is a schematic diagram showing an illuminance distribution ofthe light source apparatus shown in FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENTS

Next, with reference to the accompanying drawings, embodiments of thepresent invention will be described.

FIG. 1 is a perspective view showing a light source apparatus 10according to an embodiment of the present invention. FIG. 2 is aschematic diagram showing the light source apparatus 10 viewed in thedirection of arrow A shown in FIG. 1. FIG. 3 is a plan view showing apart of the light source apparatus 10.

As shown in FIG. 1 and FIG. 3, the light source apparatus 10 includes aplurality of light emitting devices 2 and a light guide 3. The lightemitting devices 2 are disposed in line (in the X direction shown inFIG. 1 and FIG. 3). The light guide 3 guides light emitted from thelight emitting devices 2 in a predetermined direction. The lightemitting devices 2 are disposed, for example, on a printed wiring board8. Each of the light emitting devices 2 is an LED that has three lightemitting sources of red, green, and blue (RGB). The light emittingdevices 2 emit white light of which these color lights are mixed.

Instead, each of the light emitting devices 2 may be composed of a lightemitting source of a single color or a plurality of light emittingsources of a single color. In these cases, each of the light emittingdevices 2 emits light of a single color of RGB. The light guide 3 mixeslights of different colors of RGB. The light emitting devices 2 may beinorganic light emitting devices or organic light emitting devices.

FIG. 4 is a sectional view showing a carriage into which the lightsource apparatus 10 shown in FIGS. 1 to 3 has been built. FIG. 5 is aperspective view showing a scanner apparatus as an exemplary electronicapparatus equipped with the carriage 21. The scanner apparatus 100includes a main body 24 and a cover 25. The main body 24 has a platen 23on which a sheet of a document, a photo, or the like as an exemplarylight radiating object 22 (refer to FIG. 2 and FIG. 4). The cover 25 isdisposed on the main body 24 such that the cover 25 can be opened fromor closed to the platen 23. The platen 23 is made, for example, of aglass or a resin having a high light transmissivity. Disposed in themain body 24 are a motor (not shown) and so forth that move the carriage21 in a linear direction (the Y direction shown in FIG. 1 to FIG. 5)such that the entire plane of the light radiating object 22 placed onthe platen 23 is read. In addition, disposed in the main body 24 is aguide rail 19 that guides the carriage 21 that moves. The guide rail 19is connected to a lower portion of the carriage 21, for example, asshown in FIG. 4. The structure of the scanner apparatus 100 is notlimited to such an example shown in FIG. 1 to FIG. 5. Thus, the scannerapparatus 100 may be designed to be in any proper structure whennecessary.

As shown in FIG. 4, disposed in the carriage 21 are the foregoing lightsource apparatus 10, a plurality of mirrors 11, 12, 13, 14, and 15, alens system 16 that focus an object, an optical path length adjustmentdevice 17, and an image sensor (photo-optical converting device) 18. Theplurality of mirrors 11, 12, 13, 14, and 15 are disposed such that theoptical path length from the light source apparatus 10 to the imagesensor 18 becomes as large as possible. The mirrors 11, 12, 13, 14, and15 elongate in the X direction (shown in FIG. 4). The lens system 16 maybe composed of a plurality of lenses. The optical path length adjustmentdevice 17 adjusts the optical path difference, for example, betweeninfrared light and regular light. The image sensor 18 is, for example, aCCD (Charge Coupled Device). The image sensor 18 may be a CMOS(Complementary Metal-Oxide Semiconductor) sensor instead of a CCD. Theoptical system disposed in the carriage 21 may be designed to be in anyproper structure depending on the type of the image sensor 18.

FIG. 6 is a schematic diagram showing a theory of the optical systemdisposed in the carriage 21. Linear light that exits from an exitsurface 6 (that will be described later) of the light guide 3 isradiated to the light radiating object 22. The reflected light from thelight radiating object 22 is reflected by the mirrors 11, 12, 13, 14,and 15 (refer to FIG. 4). The reflected light of the mirrors 11, 12, 13,14, and 15 enters the image sensor 18 through the lens system 16.

As shown in FIG. 2, the light guide 3 includes an incident surface 7from which light emitted from the plurality of light emitting devices 2enters, the foregoing exit surface 6 that causes light that has enteredfrom the incident surface 7 to be condensed and the condensed light toexit, and a light guide section 9 that guides the light that has enteredfrom the incident surface 7 to the exit surface 6.

The incident surface 7 is, for example, plane-shaped. Width w1 in the Zdirection (the width in the height direction) of the incident surface 7is designed to be substantially the same width as or slightly smallerthan the light emitting plane of each of the light emitting devices 2.This structure prevents light that exits from the exit surface 6 frombeing mixed with dark lines. As a result, this structure contributes tohomogenization of light.

The light guide section 9 is bent such that its volume graduallyincreases in the direction from the incident surface 7 to the exitsurface 6. The state of “the light guide section 9 is bent” may beclearly represented by a bending line as shown in FIG. 2. Instead, thestate of “the light guide section 9 is bent” may be a curved statewithout a bending line.

The light guide section 9 has a first side surface 4 that is formed on anear side of the light radiating object 22 and a second side surface 5that is formed on a far side of the first side surface 4. The first sidesurface 4 is composed of a first reflection surface 4 a and a secondreflection surface 4 b. The second side surface 5 is composed of a thirdreflection surface 5 a and a fourth reflection surface 5 b. The angleformed by the third reflection surface 5 a and the fourth reflectionsurface 5 b is represented by angle θ1, whereas the angle formed by thefirst reflection surface 4 a and the second reflection surface 4 b isrepresented by angle θ2. Angle θ1 and angle θ2 satisfy the relationshipof θ1>θ2. In other words, this relationship causes the volume of thelight guide section 9 to gradually increase in the direction from theincident surface 7 to the exit surface 6. In other words, the lightguide section 9 is formed such that the more the first reflectionsurface 4 a is apart from the incident surface 7, the more the firstreflection surface 4 a is apart from the third reflection surface 5 aand that the more the second reflection surface 4 b is apart from theincident surface 7, the more the second reflection surface 4 b is apartfrom the fourth reflection surface 5 b. In this example, the angles arebased on plane X-Y.

In particular, θ1 is set in the range from 120° to 150°. Preferably, θ1is set to 142°. In contrast, θ2 is not restricted as long as it issmaller than θ1. In other words, θ1 and θ2 are set such that the radiusof curvature of the exit surface 6 (that will be described later)becomes proper, namely light having desired light flux and light amountexits from the exit surface 6.

The exit surface 6 has a cylindrical shape section viewed in thedirection of the drawing of FIG. 2. Instead, the exit surface 6 may havean elliptical shape section or a hyperbolic curve shape section. Theexit surface 6 may be blast-finished. When the exit surface 6 isblast-finished, light that exits from the exit surface 6 can becondensed and scattered on the exit surface 6. As a result, light ismore homogeneously radiated to the light radiating object 22 than theexit surface 6 that is not blast-finished. As shown in FIG. 3, whenpitch p1 between adjacent light emitting devices 2 is larger thanoptical path length h represented by dotted lines shown in FIG. 2, itappears that color shading occurs. However, when the exit surface 6 isblast-finished, it promotes to homogenize light. As a result, opticalpath length h is allowed to be smaller than pitch p1. Thus, the lightguide 3 can be thinned or miniaturized. Although p1 is set in the rangearound from 9 to 12 mm, it may be designed to be any proper valuedepending on the size of the light emitting devices and other designingconditions. Although the radius of curvature of the exit surface 6 isset in the range around from 2 to 4 mm, it may be designed to be anyproper value when necessary.

FIG. 7 is a schematic diagram showing a simulation of light beams thatpass through the light guide 3. As is clear from the drawing, most oflight beams that have entered from the incident surface 7 are totallyreflected on the first side surface 4 and the second side surface 5 andexit from the exit surface 6. Thus, the amount of light beams that exitfrom the exit surface 6 increases. When angles θ1 and θ2 are properlyset to the foregoing values, such light beams can be achieved.

Depending on the shape of the exit surface 6 and the values of θ1 andθ2, the light guide section 9 properly spreads light that travels towardthe exit surface 6. As a result, the exit surface 6 formed in a lightcondensing shape can substantially collimate light. Thus, well-shapedlight, namely accurately liner shaped light, can be radiated.

FIG. 8 is a schematic diagram showing an illuminance distributioncharacteristic of the light source apparatus 10 according to thisembodiment of the present invention. In FIG. 8, illuminance distributiond1 is uniform in the longitudinal direction of the light sourceapparatus 10.

FIG. 9 schematically shows an illuminance distribution in the case thatthe light emitting devices 2 are disposed on both ends of a light guideplate 32. In this example, the illuminance is the strongest at thecenter of illuminance distribution d2. FIG. 10 is a schematic diagramshowing an illuminance distribution in the case that a plurality oflight emitting devices 2 are disposed, for example, immediately belowthe light guide plate 32. In this example, illuminance distribution d3varies at each of the light emitting devices 2. In the examples shown inFIG. 9 and FIG. 10, it is difficult to obtain a uniform illuminancedistribution.

As described above, according to this embodiment, since the light guidesection 9 is designed such that its volume gradually increases, thelight guide section 9 can effectively guide light that has entered fromthe incident surface 7 and that has diffused and cause the light to exitfrom the exit surface 6. In other words, the light guide section 9 canguide light that has entered from the incident surface 7 and that hasdiffused without a loss of light.

In addition, since the light guide section 9 is bent, light that hasentered from the incident surface 7 is bent at a predetermined angle andthen the light exits from the exit surface 6. Thus, while optical pathlength h of the light guide 3 is kept as large as possible, light can bediffused and homogeneously radiated. In addition, the light guide 3 andthe scanner apparatus 100 equipped therewith can be miniaturized orthinned. However, as described above, optical path length h can besmaller than pitch p1 (refer to FIG. 3).

According to this embodiment, since it is not necessary to use adiffuser sheet and so forth, the manufacturing costs of the light sourceapparatus 10 and the scanner apparatus 100 can be reduced. In addition,these omission contributes to miniaturization of the light sourceapparatus 10 and the scanner apparatus 100.

FIG. 11A and FIG. 11B are graphs showing the startup times of a CCFL andan LED of the related art. The vertical axis of each graph representsthe intensity of light, whereas the horizontal axis represents theelapsed time after power-on (unit: seconds). Thus, although the LED hasdifferences of intensities of RGB, the startup time of the LED is muchsmaller than that of the CCFL.

FIG. 12 is a side view showing a light source apparatus 30 according toanother embodiment of the present invention. In the following, thedescription of structures and functions that are the same as those ofthe light source apparatus 10 shown in FIG. 2 will be simplified oromitted and only their different points will be described.

In this embodiment, a light guide 33 shown in FIG. 12 has a shuttersection 34 c that is recessed from a first side surface 34 and that isformed between a first reflection surface 34 a and a second reflectionsurface 34 b. The shutter section 34 c has a function of blocking partof light beams that travel from an incident surface 37 to an exitsurface 36. FIG. 13 is a schematic diagram showing a simulation of lightbeams that pass through the light guide 33. Although the light guide 33has the shutter section 34 c, the light guide 33 has the same effect asthe light guide 3 shown in FIG. 2. Unless the light guide 33 has theshutter section 34 c, incident light reflected on a third reflectionsurface 35 a tends to spread and exit from an end region of the exitsurface 36 as represented by a dotted line shown in FIG. 14. Incontrast, the light guide 33 of this embodiment allows incident lightreflected on the third reflection surface 35 a to be reflected on theshutter section 34 c and the reflected light to exit from a centerregion instead of the end region of the exit surface 36.

FIG. 15A is a schematic diagram showing a simulation of light beams thatpass through the light guide 33 that has the shutter section 34 c andwhose θ1 is set to 150° or more. FIG. 15B is a schematic diagram showinga simulation of light beams that pass through the light guide 33 thathas the shutter section 34 c and whose θ1 is set to smaller than 120°.Thus, it is clear that light increasingly leaks from the light guide 33unless angle θ1 is in the range from 120° to 150°.

FIG. 15A and FIG. 15B show simulations of light beams that pass throughthe light guide 33 having the shutter section 34 c. Likewise, unlessangle θ1 is in a proper range, light leaks from a light guide that doesnot have the shutter section 34 c.

FIG. 16 is a plan view showing a part of a light source apparatusaccording to another embodiment of the present invention. Formed on anexit surface 46 of a light guide 43 of a light source apparatus 50 are aplurality of light condensing planes 46 a formed in the direction ofwhich a plurality of light emitting devices 2 are disposed. In thisexample, the light condensing planes 46 a are formed corresponding tothe light emitting devices 2 in one-to-one relationship. Instead, thelight condensing planes 46 a may not be formed corresponding to thelight emitting devices 2 in one-to-one relationship. In other words, onelight condensing plane 46 a may be formed corresponding to every two ormore light emitting devices 2. The light condensing planes 46 a may havea spherical shape section or a toroidal shape section. When the lightguide 43 is viewed from its side, it has the same shape as the lightguide 3 shown in FIG. 2 or the light guide 33 shown in FIG. 12.

The plurality of light condensing planes 46 a contribute tohomogenization of light that exits from the exit surface 46.

FIG. 17 is a plan view showing a part of a light source apparatus 70according to another embodiment of the present invention. In the lightsource apparatus 70, a light guide 53 has an incident surface 57 formedin a shape that causes light to diffuse, for example, in a prism shape.Prisms formed on the incident surface 57 may be designed in any propersize. As the diffusing shape other than the prism shape, a concavedplane may be formed on each of the light emitting devices 2. Thus, thelight guide 53 can effectively diffuse incident light that enters froman incident surface 57 and contributes to homogenization of the incidentlight.

FIG. 18 is a plan view showing a part of a light source apparatus 90according to another embodiment of the present invention. In the lightsource apparatus 90, light emitting devices 2 are disposed in such amanner that the inclining angle of each of the light emitting devices 2to the center of a light guide 63 is proportional to the distance fromthe center of the light guide 63. In other words, the inclination angleof the light emitting devices 2 disposed at an end region 63 a is thelargest in all the light emitting devices 2. Thus, the illuminance atthe end region 63 a of the light guide 63 can be prevented fromdecreasing in comparison with the other structures. As a result, theilluminance at the end region 63 a can be uniformly kept in comparisonwith the other structures.

FIG. 19A is a schematic diagram showing an illuminance distribution of aleft half of the light source apparatus 90 shown in FIG. 18. Theilluminance distribution of the right half of the light source apparatus90 is symmetrical to that of its left half. Thus, it is clear that lightdoes not largely spread to the left and right. FIG. 19B is a schematicdiagram showing an illuminance distribution of the light sourceapparatus 10 shown in FIG. 3.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alternations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

For example, at least two of the light source apparatuses 10, 30, 50,70, and 90 may be used in combinations.

In the foregoing embodiments, the scanner apparatus 100 was described asan exemplary electronic apparatus. Instead, the electronic apparatus maybe a copy machine or a multi-function machine incorporated with aprinter function.

In the foregoing embodiments, the light emitting devices were disposedin one row. Instead, the light emitting devices may be disposed in aplurality of rows.

1. A light guide, comprising: an incident surface from which lightemitted from a plurality of light emitting devices disposed in lineenters; an exit surface which is formed in a shape causing light to beconcentrated and from which the light which has entered from theincident surface exits; and a light guide section which is bent andwhose volume gradually increases in a direction from the incidentsurface to the exit surface.
 2. The light guide as set forth in claim 1,wherein the exit surface is blast-finished.
 3. The light guide as setforth in claim 1, wherein the light guide section has a side surfacewhich is disposed on a far side of a radiating object and which is bentat an angle in a range from 120° to 150°.
 4. The light guide as setforth in claim 1, wherein the exit surface has a plurality of lightcondensing surfaces in a direction of which the plurality of lightemitting devices are disposed.
 5. The light guide as set forth in claim1, wherein the light incident surface is formed in a shape which causeslight to diffuse.
 6. A light guide, comprising: an incident surface fromwhich light emitted from a plurality of light emitting devices disposedin line enters; an exit surface which is formed in a shape causing lightto be concentrated and from which the light which has entered from theincident surface exits to a light radiating object; and a light guidesection which has a first side surface disposed on a near side of thelight radiating object and a second side surface disposed on a far sideof the light radiating object and bent from the first side surface at afirst angle and which guides the light from the incident surface to theexit surface.
 7. The light guide as set forth in claim 6, wherein thefirst side surface has: a first reflection surface connected to theincident surface; and a second reflection surface connected to the firstreflection surface at a second angle which is smaller than the firstangle and to the exit surface.
 8. The light guide as set forth in claim7, wherein the second side surface has a third reflection surface whichis connected to the incident surface and which is gradually apart fromthe first reflection surface as the third reflection surface is apartfrom the incident surface.
 9. The light guide as set forth in claim 7,wherein the light guide section has a shutter section which blocks partof light passing from the incident surface to the exit surface and whichis formed between the first reflection surface and the second reflectionsurface such that the shutter section is recessed from the first sidesurface.
 10. A light source apparatus, comprising: a plurality of lightemitting devices disposed in line; and a light guide having an incidentsurface from which light emitted from the plurality of light emittingdevices enters; an exit surface which is formed in a shape causing lightto be concentrated and from which the light which has entered from theincident surface exits; and a light guide section which is bent andwhose volume gradually increases in a direction from the incidentsurface to the exit surface.
 11. An electronic apparatus, comprising: aplurality of light emitting devices disposed in line; a light guidehaving an incident surface from which light emitted from the pluralityof light emitting devices enters; an exit surface which is formed in ashape causing light to be concentrated and from which the light whichhas entered from the incident surface exits; and a light guide sectionwhich is bent and whose volume gradually increases in a direction fromthe incident surface to the exit surface; and a photoelectric convertingdevice which receives the light which has exited from the exit surfaceand has reflected by a light radiating object, and converts thereflected light into an electric signal.